Transceiver Equalization for PA AM-AM and AM-PM Error Correction
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Solution Overview
Problem
Existing transmission circuits in mobile communication devices experience amplitude-amplitude (AM-AM) and amplitude-phase (AM-PM) errors due to interactions between power amplifier circuits and RF front-end circuits, leading to undesired amplitude distortion and spectrum regrowth, particularly in wide modulation bandwidths.
Innovation Solution
The transceiver circuit employs multiple complex filters to equalize input vectors, applying frequency equalization and phase correction to generate frequency-equalized input vectors with consistent amplitudes and group delays across modulation frequencies, thereby correcting AM-AM and AM-PM errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power amplifier circuit is coupled to RF front-end circuit to amplify RF signal, then signal transmission capability is improved, but interaction between output reflection coefficient of power amplifier and input reflection coefficient of RF front-end creates voltage distortion filter causing AM-AM and AM-PM errors
Solution Approach 1:
The patent applies preliminary action by pre-equalizing the input vector before it enters the power amplifier circuit. The transceiver circuit processes the input vector through equalization filters that compensate for the anticipated AM-AM and AM-PM errors that will occur during amplification. This pre-correction ensures that even though the power amplifier and RF front-end interaction creates distortion, the overall system output maintains accurate amplitude and phase characteristics across the modulation bandwidth.
2Manufacturing precision
If frequency equalization filter is applied to input vector to correct AM-AM and AM-PM errors, then amplitude and phase accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the equalization function into the existing transceiver circuit architecture. Rather than adding a completely separate equalization system, the frequency equalization filter is integrated within the transceiver circuit that already generates the RF signal. This consolidation allows the equalization process to share hardware resources and control mechanisms with the signal generation functions, thereby reducing the overall device complexity increase while still achieving accurate AM-AM and AM-PM error correction.
3Productivity
If voltage distortion filter is created by interaction between power amplifier and RF front-end, then signal transmission is enabled, but amplitude distortion and spectrum regrowth occur particularly in wide modulation bandwidth
Solution Approach 1:
The patent applies preliminary anti-action by implementing equalization that specifically counteracts the harmful effects of the voltage distortion filter. The equalization filter is designed to produce effects that are opposite to and cancel out the amplitude distortion and spectrum regrowth caused by the interaction between the power amplifier's output reflection coefficient and the RF front-end's input reflection coefficient. This preemptive counter-action prevents the harmful effects from manifesting in the final transmitted signal, especially across wide modulation bandwidths.
Data Source
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AI summary
Phase and amplitude error correction in a transmission circuit is provided. The transmission circuit includes a transceiver circuit, a power management integrated circuit (PMIC), and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from an input vector, the PMIC generates a modulated voltage, and the power amplifier circuit(s) amplifies the RF signal(s) based on the modulated voltage. In embodiments disclosed herein, the transceiver circuit is configured to equalize the input vector using multiple complex filters to thereby correct amplitude-amplitude (AM-AM) and amplitude-phase (AM-PM) errors. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth to thereby improve efficiency and linearity of the power amplifier circuit(s) across the modulation bandwidth.